Related piperidine derivatives having antihistamine properties are disclosed in the following U.S. patents which are the only material and pertinent references known to applicants:
U.S. Pat. No. 3,806,526 issued Apr. 23, 1974, PA1 U.S. Pat. No. 3,829,433 issued Aug. 13, 1974, PA1 U.S. Pat. No. 3,862,173 issued Jan. 21, 1975, PA1 U.S. Pat. No. 3,878,217 issued Apr. 15, 1975, PA1 U.S. Pat. No. 3,931,197 issued Jan. 6, 1976, PA1 U.S. Pat. No. 3,941,795 issued Mar. 2, 1976, PA1 U.S. Pat. No. 3,946,022 issued Mar. 23, 1976, and PA1 U.S. Pat. No. 3,965,257 issued June 22, 1976.